Ischemic heart disease causes mitral regurgitation by the combination of ischemic dysfunction of the papillary muscles, and the dilatation of the left ventricle that is present in ischemic heart disease, with the subsequent displacement of the papillary muscles and the dilatation of the in mitral valve annulus.
Dilation of the annulus of the mitral valve prevents the valve leaflets from fully coapting when the valve is closed. Mitral regurgitation of blood from the leer ventricle into the left atrium results in increased total stroke volume and decreased cardiac output, and ultimate weakening of the left ventricle secondary to a volume overload and a pressure overload of the left atrium.
Chronic or acute left ventricular dilatation can lead to papillary muscle displacement with increased leaflet tethering due to tension on chordae tendineae, as well as annular dilatation.
U.S. Pat. No. 7,431,692 to Zollinger et al., which is incorporated herein by reference, describes an adjustable support pad for adjustably holding a tensioning line used to apply tension to a body organ. The adjustable support pad can include a locking mechanism for preventing slidable movement of the tensioning element in one or both directions. The locking mechanism may include spring-loaded locks, rotatable cam-like structures, and/or rotatable spool structures. The adjustable support pad may be formed from rigid, semi-rigid, and/or flexible materials, and may be formed to conform to the outer surface of a body organ. The adjustable support pad can be configured to adjustably hold one or more separate tensioning lines, and to provide for independent adjustment of one or more tensioning lines or groups thereof.
US Patent Application Publication 2007/0118151 to Davidson, which is incorporated herein by reference, describes a method and system to achieve leaflet coaptation in a cardiac valve percutaneously by creation of neochordae to prolapsing valve segments. This technique is especially useful in cases of ruptured chordae, but may be utilized in any segment of prolapsing leaflet. The technique described herein has the additional advantage of being adjustable in the beating heart. This allows tailoring of leaflet coaptation height under various loading conditions using image-guidance, such as echocardiography. This offers an additional distinct advantage over conventional open-surgery placement of artificial chordae. In traditional open surgical valve repair, chord length must be estimated in the arrested heart and may or may not be correct once the patient is weaned from cardiopulmonary bypass. The technique described below also allows for placement of multiple artificial chordae, as dictated by the patient's pathophysiology.
U.S. Pat. No. 6,626.930 to Allen et al. describes apparatus and method for the stabilization and fastening of two pieces of tissue. A single device may be used to both stabilize and fasten the two pieces of tissue, or a separate stabilizing device may be used in conjunction with a fastening device. The stabilizing device may comprise a probe with vacuum ports and/or mechanical clamps disposed at the distal end to approximate the two pieces of tissue. After the pieces of tissue are stabilized, they are fastened together using sutures or clips. One exemplary embodiment of a suture-based fastener comprises a toggle and suture arrangement deployed by a needle, wherein the needle enters the front side of the tissue and exits the blind side. In a second exemplary embodiment, the suture-based fastener comprises a needle connected to a suture. The needle enters the blind side of the tissue and exits the front side. The suture is then tied in a knot to secure the pieces of tissue. One example of a clip-based fastener comprises a spring-loaded clip having two arms with tapered distal ends and barbs. The probe includes a deployment mechanism which causes the clip to pierce and lockingly secure the two pieces of tissue. U.S. Pat. No. 6,629,534 to St. Goar et al. describes methods, devices, and systems are provided for performing endovascular repair of atrioventricular and other cardiac valves in the heart. Regurgitation of an atrioventricular valve, particularly a mitral valve, can be repaired by modifying a tissue structure selected from the valve leaflets, the valve annulus, the valve chordae, and the papillary muscles. These structures may be modified by suturing, stapling, snaring, or shortening, using interventional tools which are introduced to a heart chamber. Preferably, the tissue structures will be temporarily modified prior to permanent modification. For example, opposed valve leaflets may be temporarily grasped and held into position prior to permanent attachment.
U.S. Pat. No. 6,752,813 to Goldfarb et al. describes methods and devices for grasping, and optional repositioning and fixation of the valve leaflets to treat cardiac valve regurgitation, particularly mitral valve regurgitation. Such grasping will typically be atraumatic providing a number of benefits. For example, atraumatic grasping may allow repositioning of the devices relative to the leaflets and repositioning of the leaflets themselves without damage to the leaflets. However, in some cases it may be necessary or desired to include grasping which pierces or otherwise permanently affects the leaflets. In some of these cases, the grasping step includes fixation.
US Patent Application Publication 2003/0105519 to Fasol et al. describes artificial chordae having a strand member and a first and second pair of sutures at either longitudinal end of the strand member. The artificial chordae is preferably a unitary unit, formed from inelastic flexible material. In one embodiment, the artificial chordae comprises multiple strand members joined together at a joined end. Different sized artificial chordae are provided sized to fit the patient's heart. The appropriately sized artificial chordae is chosen by using a chordae sizing gauge having a shaft and a transverse member, to measure the space within the patient's heart where the artificial chordae is attached.
The following patents and patent application publications may be of interest:
PCT Patent Application Publication WO 07/136783 to Cartledge et al.
U.S. Pat. No. 5,306,296 to Wright et al.
U.S. Pat. No. 6,569,198 to Wilson et al.
U.S. Pat. No. 6,619,291 to Hlavka et al.
U.S. Pat. No. 6,764,510 to Vidlund et al.
U.S. Pat. No. 7,004,176 to Lau
U.S. Pat. No. 7,101,395 to Tremulis et al.
U.S. Pat. No. 7,175,660 to Cartledge et al.
US Patent Application Publication 2003/0050693 to Quijano et al
US Patent Application Publication 2003/0167062 to Gambale et al.
US Patent Application Publication 2004/0024451 to Johnson et al.
US Patent Application Publication 2004/0148021 to Cartledge et al
US Patent Application Publication 2004/0236419 to Milo
US Patent Application Publication 2005/0171601 to Cosgrove et al.
US Patent Application Publication 2005/0216039 to Lederman
US Patent Application Publication 2005/0288781 to Moaddeb et al.
US Patent Application Publication 2007/0016287 to Cartledge et al.
US Patent Application Publication 2007/0080188 to Spence et al.
US Patent Application Publication 2009/0177266 to Powell et al.
The following articles may be of interest:
O'Reilly S et al., “Heart valve surgery pushes the envelope,” Medtech Insight 8(3): 73, 99-108 (2006)
Dieter R S. “Percutaneous valve repair: Update on mitral regurgitation and endovascular approaches to the mitral valve,” Applications in Imaging, Cardiac Interventions, Supported by an educational grant from Amersham Health pp. 11-14 (2003)